Swash plate internal combustion engine operating on the two-stroke cycle



Jan. 24, 1933.

-H. R. RICARDO SWASH PLATE INTERNAL COMBUSTION ENGINE OPERATING ON THE TWO-STROKE CYCLE Filed July 27, 1931 Patented Jan. 24, 1933 UNITED STATES HARRY RALPH RICARDO, OF LONDON, ENGLAND SWASE PLATE INTERNAL COMBUSTION ENGINE OPERATING ON THE TWO-STROKE CYCLE Application filed July 27, 1931, Serial No. 553,439fand in Great Britain September 29, 1930.

This invention relates to multi-cylinder internal combustion engines operating on the two-stroke cycle of the kind in which the engine shaft carries a swash plate on which act working pistons arranged in cylinders disposed around and with their axes parallel to the axis of rotation of the engine shaft, and more particularly to engines of the above kind in which a series of reciprocating charging or scavenging pumps having their pistons driven from the swash plate or from the working pistons are disposed around the axis of the engine shaft.

In such engines it has been proposed to provide a single rotaryvalve controlling the flow of the scavenging charge into and out of the scavenging pump cylinders, this valve distributing the scavengin charge in turn to the several internal com ustion cylinders, and the object of the present invention is to provide a more convenient and. compact construction than that hitherto proposed.

According to the present invention the main shaft which carries the swash plate or slant is formed hollow and the scavenging or charging pumps are adapted to deliver the gaseous scavenging charge through the interior of this shaft to the scavenging or inlet ports in the internal combustion engine cylinders. Preferably the flow of scavenging charge from the atmosphere or other source into the scavenging or charging pump cylinders and from these cylinders into the hollow main shaft is controlled by a rotary valve disposed coaxially with and driven by the hollow main shaft. In any case the scavenging charge delivered through the hollow main shaft may either pass to a scavenging belt which is common to the scavenging ports of all the internal combustion cylinders, or the hollow engine shaft may be provided with one or more ports in its wall which communicate in turn with ports leading respectively to the scavenging ports of the several internal combustion cylinders so that the hollow main shaft acts as a valve controlling and determining the period of flow of scavenging charge in turn to each internal combustion cylinder The invention may be applied to an engine of the type referred to having a single swash plate and a single set of working pistons but is particularly applicable to engines of the type in question in which each internal combustion cylinder contains two oppositely moving working pistons controlling respectively the scavenging or inlet ports and the exhaust ports and acting respectively on two swash plates on the engine shaft. In this case the pistons of the scavenging or charging pumps are conveniently operated directly through piston rods from the Working pistons which control the scavenging or inlet ports.

The invention may be carried into practice in various ways but one construction according to this invention is illustrated somewhat diagrammatically in sectional side elevation by way of example in the accompanying drawing, in which:

Figure 1 is a sectional side elevation; and

Figure 2 is a cross-section through the valve member employed in the construction shown in Figure 1, this section being taken at right angles to the length of the valve member and in a plane midway between its ends,

In the construction illustrated the engine comprises a hollow engine shaft A mounted to rotate in a casing B in which are formed a series of open-ended cylinders, C, C arranged around and having their axes parallel to the axis of the engine shaft. Mounted to reciprocate in each cylinder is a pair of oppositely moving working pistons D, D which act through hemispherical bearing members D respectively upon two swash plates A A formed on the main shaft. Each of the pistons D is adapted to control exhaust ports C communicating with an-exhaust belt C formed in the cylinder wall, while each of the other istons D controls inlet or scavenging ports 4 which communicate with a scavenging belt C formed in the cylinder wall and common to the scavenging ports of all the cylinders, this belt communicating in turn through ports C with ports A passing to the interior of the hollowshaft A.

Formed in the casing B on the side of the swash plate A remote from the internal combustion cylinders are a series of scaveng- I ing cylinders E each of which is coaxial with one of the internal combustion cylinders 0, C Each scavenging cylinder E contains a scavenging piston F which is connected by a piston rod 1 to the adjacent working PIS- ton D so as to be reciprocated thereby. Each [scavenging pump constituted by a cylinder E and piston F is of the double-acting type and to this end the ends of the scavenging cylinders E are provided with ports E E each of which acts'both as an inlet and as adelivery port. The ports E E are controlled by a rotary tubular valve G disposed coaxially with and conveniently arranged withinthe hollow engine shaft A. This valve G is provided with aninlet passage G communicating through one end of the valve with the atmosphere and also communicating with inlet ports G G in its circumferential wall adapted to register respectively with the ports E E during the suction periods of the ends of the cylinders with which these ports communicate. The end of'the valve G remote from the inlet end communicates with the interior of the hollow shaft A and also with a delivery chamber G within the valve and surrounding the inlet passage G, from which lead delivery ports G, G which are adapted to register respectively with the ports El, E during the delivery periods of the ends of the cylinders E with which these ports communicate. A 'baffle or plug A is arranged within the hollow shaft A at a point on the sides of the ports A remote from the valve G so as to prevent the escape of scavenging air along the shaft and cause this air to pass through the ports A and (1 into the cylinders C, C.

The operation of the engine is as .follows. The swash plates A A are so formed on the shaft A that the pistons D, D move in opposite directions. During each inward movement of one of the pistons D the pump piston F attached to it is moved to the right in the drawing and during this period the port E of the cylinder E of that piston registers with the port G in the valve G so that air is delivered to the interior of the hollow shaft A, the port E at the other end of the pump cylinder communicating during this period with the port G so that a fresh charge of air is drawn into the other end of the cylinder. At the same time the piston F secured to the piston D which acts on the diametrically opposite portion of the swash plate is moving to the left in the drawing on its outstroke so as to draw air through its port E which is then in communication with the port G of the valve G and to force air into the interior of the shaft A fromits other end through the port E which is then in communicatior with the port G.

At the end of the outstroke of the pair of pistons in any cylinder, the piston D first uncovers the exhaust ports 0* to permit the where ithas been compressed by the escape of burnt gases, and immediately afterwards the piston D uncovers the inlet or scavenging ports C so as to admit a scavengmg charge from the interior of the shaft A P pistons F in the manner described a ove. The pair of working pistons D, D then move towards one another again and compress the charge between them, the corresponding pump piston F being moved to the right in the drawing so as to deliver a further aircharge from the right hand end 'of its cylinder E through the ports E G into the mterior of the shaft A and draw a fresh air charge into the other end of its cylinder from the atmosphere through the 'ports E G.

In some cases the ports A and C may cooperate so as to control the period of delivery of the scavenging charge therethrougli into each individual working cylinder.

It will be seen that the arrangement above described provides a simple and compact construction which enables the scavenging air to be' delivered readily to the scavenging ports even when, as with high speed engines, the cylinders are closely packed around the engine shaft, thus eliminating the difliculties experienced with the prior construction referred to above wherein the scavenging air had to be passed out again from the interior of the rotary valve to an external casing and thence to the scavenging ports of the internal combustion engine cylinders at a point outside the main casing, which was inconvenient and reduced accessibility.

It is to be understood that the construction more particularly described above is given by way of example only and that constructional details may be modified without departing from this invention.

Further, although the invention has been described with particular reference to an engine in which a scavenging charge of air is delivered to each cylinder, it may be applied also to engines employlng a scavenging charge constituted by. a combustible vapourized mixture.

What I claim as m invention and desire to secure by Letters atent is 2-.-

l. A multi-cylinder internal combustion engme operating on the two-stroke cycle including in combination a hollow engine shaft, a swash plate on the engine shaft, a series of working cylinders disposed around the engine shaft with their axes parallel to such shaft and having scavenging ports communicating with the interior of the,shaft,va series of scavenging pump cylinders separate tary valve coaxial with the hollow engine der is brought into communication with the interior of the hollow engine shaft during its delivery period and into communication with a source of scavenging fluid during its suction period.

2. A multi-cylinder internal combustion engine operating on the two-stroke cycle including in combination a hollow engine shaft, a swash plate on the engine shaft, :1, series of working cylinders disposed around the engine shaft with their axes parallel to such shaft and having scavenging ports communicating with the interior of the shaft, a series of separate scavenging pum cylinders of larger diameter than the wor ing cylinders disposed around and with their axes parallel to the axis of the engine shaft with inlet and outlet ports at both ends of each of the scavenging pump cylinders, double-acting pistons in the pump cylinders, operative con.- nections between the swash plate and the pump pistons, and a.rotary valve coaxial with the hollow engine shaft whereby each end of each pump cylinder is brought into communication with the interior of the hollow engine shaft during its delivery period and into communication with a source of scavenging fluid during its suction period.

3. A multi-cylinder internal combustion engine operating on the two-stroke cycle ineluding in combination a hollow engine shaft having scavenging ports in'its walhtwo swash plates on the engine shaft, a casing surrounding the engine shaft, a series of open-ended working cylinders formed in the casing between the swash plates so as to lie around the engine shaft with their axes parallel to such shaft and having scavenging ports which communicate with'the scavenging ports in the engine shaft, the working cylinders also having exhaust ports, two pistons disposed in each cylinder and controlling respectively the scavenging and exhaust ports, operative connections between the pistons controlling the scavenging ports and one swash plate and between the pistons controlling the exhaust ports and the other swash plate, a series of separate scavenging pump cylinders disposed around and with their axes parallel to the axis of the engine shaft with inlet and outlet ports at both ends of each scavenging pump cylinder, double-acting pistons in the pump cylinders, operative connections between the pump pistons and the swash plate on which act the pistons controlling the scavenging ports, and a rotary valve disposed concentrically with the hollow engine shaft and adapted to bring the port at each end of each pump cylinder into communication with the interior of the hollowengine shaft during its delivery period and intocommunicatlon with a source of scavenging fluid during its suction period.

4. A multi-cylinder internal combustion engine operating on the two-stroke cycle including in comblnation a hollow engine shaft having scavengin ports in its wall, two

swash plates on t 'e engine shaft, a'casing surrounding the engine shaft, a series of open-ended working cylinders formed in the casing between the swash plates so as to lie around the engine shaft with their axes parallel to such shaft and having scavenging ports which communicate with the scavenging ports in the engine shaft, the working cylinders also having exhaust ports, two pistons disposed in each cylinder and controlling respectively the scavenging and exhaust ports, operative connections between the pistons controlling the scavenging ports and one swash plate and between the pistons controlling the exhaust ports and the other swash plate, a series of separate scavenging pump cylinders of larger diameter than the working cylinddrs disposed around and with their axes parallel to the axis of the engine shaft with inlet and outlet ports at both ends of each scavenging pumpvcylinder, double-acting pistons in the pump cylinders, operative connections between the pump pistons and the swash plate on which act the pistons controlling the scavenging ports, and a rotary valve disposed concentrically with the hollow engine shaft and adapted to bring the port at each end of each pump cylinder into communication with the interior of the'hollow engine shaft during its delivery period and into communication with a source of scavenging fluid during its suction period.

5. A multi-cylinder internal combustion engine operating on the two-stroke cycle including, in combination a hollow en 'ne shaft, a swash plate on the engine sha a series of working cylinders disposed around the engine shaft with their axes parallel to such shaft and having scavenging ports communicating with the interior of the shaft, a series of scavenging pump cylinders separate from the working cylinders disposed around andassociated with the pump cylinders for placing each end of each pump cylinder into communication with the interior of the hollow engine shaft during its delivery period and into communication with a source of scavenging fluid during its suction period.

In testimony whereof I have signed my name to this specification.

HARRY RALPH RICARDO. 

